A Dynamic Revetment and Reinforced Dune as "Natural" Forms of Shore Protection in an Oregon State Park

Erosion in Cape Lookout State Park on the Oregon coast removed a line of high dunes that had existed between the ocean beach and park facilities, so winter storms were able to flood the park grounds. Shore protection was needed, but it was decided that a conventional quarry-stone revetment or seawall would not be used in this park setting. Instead, the decision was made to construct a dynamic revetment, designed to be similar to a natural cobble beach, backed by an artificial dune reinforced with a core of sand-filled geotextile bags. Since their construction in 2000, we have monitored the structures in a program of periodic surveys, measurements of cobble mobility through tagging, and analyses of tides and wave runup compared with structure elevations. To date the structures have survived three winters, including major storms that resulted in some overtopping. Thus far this natural form of shore defense has proved to be successful in protecting the State park from significant storm damage, but their long-term stability remains uncertain.